These 15 frugal billionaires have answered that question for real, and their response is “not much.”

Instead of dropping dough on jets, yachts, and mansions, they have saved up, lived modestly, and given away huge amounts of money to charity.

Warren Buffett, chairman and CEO of Berkshire Hathaway

Net worth: US$46-billion

Frederic J. Brown/AFP/Getty Images

Buffett still lives in the Omaha, Nebraska, home he bought for US$31,500 more than 50 years ago.

He doesn’t own a yacht because, as he puts it, “Most toys are just a pain in the neck.” When he married his second wife, rather than a lavish affair, it was a brief afternoon wedding at his daughter’s house in Omaha.